--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/llvm/test/TableGen/cast-string.td	Tue Jun 08 06:07:14 2021 +0900
@@ -0,0 +1,59 @@
+// RUN: llvm-tblgen %s | FileCheck %s
+// RUN: not llvm-tblgen -DERROR1 %s 2>&1 | FileCheck --check-prefix=ERROR1 %s
+
+// This file tests the !cast bang operator with the result type string.
+
+defvar IntList = [0, 1, 2, 3, 4, 5, 6];
+
+// CHECK: def Rec0
+// CHECK:   string str3 = "a string here"
+
+def Rec0 {
+  string str = "a string";
+  string str2 = !cast<string>(str);
+  string str3 = !cast<string>(str # " here");
+}
+
+// CHECK: def Rec1
+// CHECK:   string str = "42 -108"
+
+def Rec1 {
+  int int1 = 42;
+  int int2 = -108;
+  string str = !cast<string>(int1) # " " # !cast<string>(int2);
+}
+
+// CHECK: def Rec2
+// CHECK:   string str = "0, 1"
+
+def Rec2 {
+  bit bit1 = false;
+  bit bit2 = true;
+  string str = !cast<string>(bit1) # ", " # !cast<string>(bit2);
+}
+
+// CHECK: def Rec3
+// CHECK:   string str = "5 and 37"
+
+def Rec3 {
+  bits<4> bits1 = 0b0101;
+  bits<8> bits2 = 0b00100101;
+  string str = !cast<string>(bits1) # " and " # !cast<string>(bits2);
+}
+
+// CHECK: def Rec4
+// CHECK:   string str = "Rec1, Rec2"
+
+def Rec4 {
+  string str = !cast<string>(Rec1) # ", " # !cast<string>(Rec2);
+}
+
+#ifdef ERROR1
+
+// ERROR1: nitializer of 'str' in 'Rec5' could not be fully resolved
+
+def Rec5 {
+  string str = !cast<string>(IntList);
+}
+
+#endif